Search results for "sinter"

Polymer-matrix route to (Bi, Pb)2Sr2Ca2Cu3O10+δ: The role of Ca2CuO3☆

1993

Abstract The use of polyethylenimine as active matrix agent has provided a fast synthesis method for (Bi, Pb)2Sr2Ca2Cu3O10+δ, starting from aqueous acetic solutions combined with careful control of the procedural variables. The 110 K phase is obtained as the only superconducting phase after sintering in air during 42 h at 860°C. This technique yields homogeneously sized, large (ca. 20 μm) platelets of the superconducting material. The presence of an excess of calcium and copper over the stoichiometric requirements accelerates the formation of the superconducting phase. This excess, which appears in the resulting material as Ca2CuO3, influences the superconducting properties, other than Tc, …

Microscopic Studies of YBCO-Based Polycrystalline Materials

1997

Improvement of the critical current density of spark plasma sintered MgB2by C60addition

2010

We investigated the influence of fullerene (C60) addition on the superconducting parameters of MgB2 bulk samples obtained by spark plasma sintering (SPS). It was found that 1.5?wt% C60 addition leads to the reduction of the critical temperature by a few K, whereas the magnetically determined critical current density increases by approximately one order of magnitude in an applied magnetic field H = 70?kOe at temperature T = 10?K. This indicates substitution of B by C in C60 added MgB2 processed by SPS, contrary to some data reported in the literature obtained using conventional methods. For our relatively large specimens, the occurrence of macroscale flux jumps was observed over a wide (H, T…

Fast synthesis of single-phased 110 K bismuth superconductor by freeze-drying of acetic precursors. Kinetic role of calcium and copper oxides

1993

Abstract Although the usefulness of solution procedures to improve the synthesis of bismuth HTSC has been argued, an adequate control of the procedural variables has allowed us to isolate the 110 K phase as the only superconducting phase after such a short sintering time as 22 h. The precursors used have been freeze-dried powders resulting from acetic solutions containing excess Ca and Cu. TGA-DTA and XRD experiments have been performed to follow the subsequent solid-state reaction processes. The initial formation of a mixed bismuth-lead oxoacetate, as intermediate to (Bi 1− y Pb y ) 2 CuO 4 , and the presence of an excess of Ca 2 CuO 3 in the last reaction step are two of the main factors …

Polymer solution processing of (Bi, Pb)SrCaCuO

1991

Abstract A simple polymer processing route to the 110 K phase (Bi, Pb) 2 Sr 2 Ca 2 Cu 3 O 10+δ superconductor has been developed. The influence of the polymer to metal starting ratio, as well as the sintering temperature and time on the quality of the resulting superconducting powders has been studied by XRD, a.c. susceptibility and resistivity measurements. Microstructure of ceramic compacts has been studied by SEM, and qualitatively analysed by EDS for compositional homogeneity. The results indicate that the polymer synthesis route described here may offer a good alternative to the conventional solid state preparation methods towards attaining homogeneous 110 K superconductor powder withi…

Interface Diffusion Controlled Sintering of Atomically Clean Surfaces of Metals

2003

Environmental modelling of aluminium based components manufacturing routes: Additive manufacturing versus machining versus forming

2018

Abstract Additive Manufacturing represents, by now, a viable alternative for metal-based components production. Therefore the designer, often, has to select among three options at process design stage: subtractive, mass conserving, and additive approaches. The selection of a given process, besides affecting the manufacturing step impact, influences significantly the impact related to the material production step. If the process enables a part weight reduction (as the Additive Manufacturing approaches do) even the use phase is affected by the manufacturing approach selection. The present research provides a comprehensive environmental manufacturing approaches comparison for components made o…

Initial Preparation and Characterization of Single Step Fabricated Intermediate Temperature Solid Oxide Fuel Cells (IT-SOFC)

2013

In this study, facile tape casting process has been successfully carried out to fabricate an unit anode supported intermediate temperature solid oxide fuel cell (IT-SOFC) with four different layers: a composite cathode which is a mix of La0.6Sr0.4Co0.2Fe0.8O3 (LSCF48) and Gd0.1Ce0.9O1.9 (GDC10), GDC10 as thin electrolyte layer, NiO-GDC10 without pore former as thin anode functional layer (AFL), and anode support layer of NiO-GDC10 with carbon pore former. The multi-layer was sintered once to produce an unit planar cell. An OCV of 1.002 V at 500 °C, and maximum power density of 466 mW cm–2 at 648 °C are obtained. These results indicate negligible leakage of fuel through electrolyte. Furtherm…

Analogical Modeling and Numerical Simulation for Sintering Phenomena

2013

In this paper the authors propose an approach for analogical modeling and numerical simulation of the phenomena of sintering, taking into account different cases depending on the type of energy used in the process of aggregation and the nature of the material powder, using a software which simulates the propagation and the control of the temperature. Many physical phenomena encountered in science and engineering can be described mathematically through partial differential equations (PDE) and ordinary differential equations (ODE) such as propagation phenomena, engineering applications, hydrotechnics, chemistry, pollution a.s.o. There may be situations when the exact establish of the analytic…

Ceria-based electrolytes prepared by solution combustion synthesis: The role of fuel on the materials properties

2016

Ce0.8Sm0.2O2 − xpowders were synthesized by solution combustion synthesis using citric acid, cellulose and sucrose as single, or intimately mixed, fuels. The powders were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, N2sorption at −196 °C, H2-temperature programmed reduction and thermogravimetric analyses. Textural properties of the powders were shaped by the peculiar employed fuel. The study of reducibility revealed that oxygen vacancies formation is mainly influenced by both parameters, specific surface area and total pore volume. The different tendency toward reduction played a key role in sintering under reducing atmosphe…